Built shaft brake discs are employed in particular for rail vehicles, and through the built shape of the shaft brake discs these can be assembled from multiple individual components.
A built shaft brake disc is to mean a shaft brake disc which is put together of at least two components. Here, a built shaft brake disc is to describe in particular a brake disc that has two friction rings which are not formed in one piece and structure-uniformly with one another, for example as is known in a casting method, but which are individually provided and preferably assembled into a friction ring pair by further elements. As a further individual part, the hub in this case can be joined to the friction ring pair in the assembly.
Known are for example shaft brake discs having a hub, on which two friction rings are attached parallel to and spaced from one another. Between the friction rings, supporting pins or bolts can extend which are embodied to absorb axially acting pad contact pressure forces. In particular in the case of heavy rail vehicles, the pad contact pressure forces which are applied onto the friction ring pair by the brake linkage via the brake pads can reach very high values. From this results the requirement of embodying shaft brake discs with supporting pins or bolts arranged between the friction rings in a suitably stiff and mechanically highly loadable manner.
In addition to this, good heat removal is required and it is frequently provided that an airflow is generated which axially flows onto the shaft brake disc for example on the hub side and flows out radially on the outside. By way of this air throughput the brake disc can be cooled through heat convection and the airflow is generated through the rotation of the shaft brake disc about its axis of rotation. In particular in the case of cast shaft brake discs, casting geometries between the friction rings are known, which simulate the geometry of a radial fan, so that the corresponding air throughput by way of the shaft brake disc is obtained.
Substantially two types of ventilation are distinguished, the described radial ventilation type and a tangential ventilation type. If a shaft brake disc has supporting pins or bolts between the friction rings, these bring about a rather tangential ventilation. Through the rotation of the shaft brake disc the surface of the supporting pins or bolts is subjected to a tangential incident flow, as a result of which heat is discharged through convection. Here, the effect can be observed that the flow medium likewise slightly flows from the inner diameter to the outer diameter, as is also the case with the radial fan. However, this effect plays only a subordinate role so that substantially an axial airflow is obtained. Important here is an optimal arrangement and dimensioning of the supporting pins or bolts so that major heat dissipation is achieved.
In particular, built shaft brake discs are known as ceramic brake discs which comprises friction rings of a ceramic material, generally however of a material from the group of carbons. Frequently the hub of such non-metallic brake discs is produced from a steel material, and elaborate connecting geometries are required in order to avoid heat-induced distortions between the ceramic or carbon material and the metallic hub for receiving the friction rings.